1. Field of the Invention
This invention relates to a novel photoconductive film and an electrophotographic photosensitive member of high sensitivity using said photoconductive film.
2. Description of the Prior Art
Heretofore, there have been disclosed pigments and dyes exhibiting photoconductivity in many literatures. For example, RCA Review, Vol. 23, pp. 413-419 (1962.9) disclosed photoconductivity of a phthalocyanine pigment, and U.S. Pat. Nos. 3397086 and 3816118 discloses an electrophotographic photosensitive member employing a phthalocyanine pigment. Further, as an organic semiconductor used in an electrophotographic photosensitive member, there is mentioned, for example, a pyrylium type dye disclosed in U.S. Pat. Nos. 4,315,983 and 4,327,169 and "Research Disclosure" 20517 (1981.5), a methine sequaric acid dye disclosed in U.S. Pat. No. 3,824,099, a disazo pigment disclosed in U.S. Pat. Nos. 3,898,084 and 4,251,613, or the like.
Such organic semiconductors can be prepared easily as compared with inorganic semiconductors, and also can be prepared as compounds having photoconductivity sensitive to a light of a desired wavelength range. Electrophotographic photosensitive members constituted of such an organic semiconductor film formed on a conductive substrate have advantageously good color sensitivity. However, there are only a few organic semiconductors having practically good sensitivity and durability. In particular, as the result of recent development of low power semiconductor laser, there are actively developed organic semiconductors of a high sensitivity characteristics as to long wavelength lights such as those of 700 nm or more, but compounds having a large light absorbing coefficient as to long wavelength lights are, in general, thermally unstable and are liable to be decomposed due to even a slight temperature rise. Therefore, electrophotographic photosensitive members sensitive to infrared ray are practically difficult to be produced.